LONDON, United Kingdom — A decade or so ago, the average retailer’s athletic wear offering was limited to basic t-shirts and trainers — clothing that was practical for exercise, but nothing else.

Today however, fuelled by increasingly casual dress codes and a growing consumer focus on health and wellness, looking like you have an active lifestyle has become cool and athletic wear has become part of the everyday wardrobe.

“This idea of being healthy and sporty and fit has become the new sexy … There’s a desire to look sporty even if you aren’t practising any sport,” says Bernadette Kissane, apparel and footwear analyst at Euromonitor.

This shift has led to the rise of the so-called ‘athleisure’ category — clothing that marries the functionality and aesthetic of activewear with the desirability of catwalk trends. Demand for fashion-inflected yoga leggings and crop tops helped drive the global activewear market to a staggering $265 billion in 2015, up from $196 billion in 2010, according to Euromonitor. And the market shows no signs of slowing down, with global sales predicted to grow at 4.4 percent CAGR through 2020.

For existing sports brands and retailers, this trend presents an obvious opportunity. But, while some, like Nike, Adidas, Foot Locker and JD Sports, have been riding the athleisure wave with great success, many have struggled. This past year has seen Sports Authority, City Sports and Vestis Retail Group, parent company of Eastern Mountain Stores, Bob’s Stores and Sport Chalet, file for bankruptcy in the US, while in the UK Sports Direct reported that pre-tax profits for the year to April 2016 were down 15 percent. So what are the necessary requirements for a successful athleisure strategy?

Established players in the activewear market were well placed to tap the athleisure trend when it first emerged, as they were already familiar to consumers. “The reason why sports brands such as Nike and Adidas have done so well is they already had that brand image, the prestige you’d want to be associated with,” explains Kissane. “The fact that [this trend] is more status driven, and wanting to look cool and sexy, than it is actually being healthy and fit, [means] you then want to be associated with the brands in that area.”

“They have built up brand affinity over the years and consumers are accustomed to buying brands they are familiar with,” agrees Diana Smith, senior research analyst, retail and apparel at Mintel. They also have a proven track record of performance-quality product, which is still a core attribute of activewear, even if a garment is not actually going to be worn for exercise, Smith adds.

Multi-brand activewear retailers were less appealing in the eyes of the athleisure consumer. “What they had sold in the past was really performance wear. You went in, you bought your tennis shoes, your running shoes, your wick-away, and it was generally not very attractive but it functioned,” explains Robert Burke, chief executive of consultancy Robert Burke Associates.

Nike and Adidas already had that brand image, the prestige you’d want to be associated with.

“It’s not the sort of environment and soul of what athleisure is — that balance between fitness and fashion and the trend of wellness,” agrees Wendy Liebmann, chief executive of consultancy WSL Strategic Retail.

Investing in the in-store experience to attract the largely female and fashion-conscious athleisure consumer is crucial for retailers attempting to capitalise on the opportunity. “It requires a very different design sensibility, a very different approach — not focused overly on items and products and tickets and prices and discounts and mark downs, but focusing more on presenting the whole assortment,” says Adheer Bahulkar, a partner in the retail practise of global strategy and management consultant firm AT Kearney.

Indeed, Sports Authority’s inability to invest in store rejuvenation — the result of crippling debt from a $1.4 billion leveraged buyout by private equity firm Leonard Green & Partners in 2006 — was a significant factor in its demise.

“That’s been a misstep in this sector — not getting their fair share of women,” says Mintel’s Smith.

In comparison, in 2015, Dick’s Sporting Goods, launched Chelsea Collective, a dedicated women’s fitness and lifestyle boutique, which currently has two locations, in recognition that its typical stores — which cater to a wide range of sports, from golf to hunting to martial arts — weren’t the ideal setting for athleisure.

“They created a totally new format that said, ‘If we are going to sell this type of product … then we need to create a totally different environment for it,’” explains Liebmann. “They understood that they couldn’t force fit it into this sporting motif where they’re selling everything. They understood that they needed to separate it out.”

In a similar move, Foot Locker has opened over 30 Six:02 stores, an elevated retail concept for women first launched in 2012, as well as dozens of Lady Foot Locker stores.

Catering to the fashion element of the athleisure trend is also crucial to succeeding in this shifting sportswear market. “[They] can’t just be geared towards athletes and they have to have a fashion-interesting aspect to it,” says Burke. “Now it’s become the expectation of the consumer today that they expect to have stylish and fashionable athletic wear.”

In order to appeal to the consumer who is wearing athleisure items to look stylish rather than do sport, the likes of Nike, Adidas and Under Armour have noticeably infused their offering with more fashion-led designs. “Those brands are pushing more into a fashion orientation as opposed to just a professional sports orientation. If you look at some of the styling, the colouration, the fabrications, the silhouettes they began to push out, it became a broader fashion statement,” says Liebmann.

They have also employed savvy advertising campaigns and designer and celebrity collaborations. Adidas, which pioneered fashion-active collaborations in 2003 with Yohji Yamamoto, has worked with designers including Alexander Wang, Stella McCartney and Raf Simons, while earlier this year, Nike announced a new collection with Louis Vuitton’s Kim Jones, and Puma released collaborations with both Kylie Jenner and Rihanna, whose second “Fenty x Puma” collection showed during Paris Fashion Week. And instead of using professional athletes in their advertising, recent Nike campaigns have featured Karlie Kloss and Bella Hadid, as well as comedian Kevin Hart, while Under Armour cast Gisele as the star of its 'I Will What I Want' campaign. “What you see [when you look at those adverts] is not an athlete,” explains Burke. “It makes them more approachable to a new customer base.”

It’s going to be really important to continue to innovate — the industry is so crowded.

For multi-brand sporting goods retailers, catering to athleisure’s fashionable consumer means ensuring they have the right product from the right brands. Both Foot Locker in the US and JD Sports in the UK have focused on a more prestigious product offering, stocking hot, of-the-moment products including Fenty x Puma and Kanye West’s Yeezy Adidas collection. This approach seems to be working. For 2015, Foot Locker reported a net income of $541 million, up from $520 million in 2014, while JD Sports reported a 20 percent increase in revenue to £971 million for the first half of 2016.

Some sports retailers have also introduced their own athleisure-inspired private labels to cater to this new fashion-focused consumer. Since 2014, Dick’s Sporting Goods has partnered with country music singer Carrie Underwood to create an accessibly-priced athleisure line, Calia by Carrie Underwood.

As the primary consumer of this new trend, women have become an important target in brands and retailers’ athleisure strategies. Along with expanded product ranges, dedicated stores and events have also been used to capture this consumer. In 2014, Nike opened its first women-only store in Newport, California, followed by similar spaces in London and Shanghai. The brand also hosts events such as its NikeWomen Victory Tour marathons. Showing a similar commitment, earlier this year Adidas hired former Lululemon chief executive Christine Day to advise them on targeting women.

But as a flurry of other industry players have moved to take advantage of the athleisure sector — including Selfridges, which now boasts a dedicated luxury athleisure department, and Beyoncé and Sir Philip Green’s Ivy Park label — the market has become significantly more competitive.

Looking forward, “it’s going to be really important to continue to innovate — the industry is so crowded,” says Smith. “There are going to be winners and there are going to be losers.”